U.S. Pat. No. 4,974,618 to Nysted discloses a method and apparatus for the foam cleaning of upholstery fabrics. The apparatus includes a generally hollow head having two foam mixing chambers in close proximity to a vacuum chamber. Foam is generated adjacent the fabric to be cleaned by admixing pressurized air and a liquid foam-producing agent in the two mixing chambers. The air pressure directs the foam from the second mixing chambers towards the fabric. Two screens are used to control the consistency and application of foam. Suction is simultaneously provided in the vacuum chamber so that the foam is rapidly and continuously recovered. A brush means is positioned between the second mixing chamber, and the vacuum chamber to further agitate the foam and fabric to be cleaned, and to help create a partial pressure when the moving foam is applied to the surface of a fabric.
While a foam cleaning method will clean fabrics, foam has its drawbacks in that it leaves a residue on the fabric which is difficult if not impossible to remove.
In addition to foam cleaning methods and apparatus, a method referred to as steam cleaning is also commonly employed to clean fabric and fabric-like surfaces, especially upholstery. As noted in the '618 patent to Nysted, U.S. Pat. No. 4,083,077 discloses that steam cleaning methods and apparatus typically employ a hand tool, which is associated with a steam cleaning machine, for cleaning carpets, as well as upholstery and other fabrics. The hand tool embodies a generally hollow head defining a cleaning agent chamber with a bottom opening, and a vacuum chamber with a bottom opening positioned forward of the cleaning agent chamber. The operator squeezes a trigger to release a cleaning fluid solution to the cleaning agent chamber where it is sprayed into the pile of the underlying fabric. As the operator pulls the hand tool in the direction of the cleaning agent chamber, suction from the vacuum chamber is applied to remove the moisture previously sprayed onto the fabric.
U.S. Pat. No. 4,654,925 to Grave discloses a type of steam cleaning machine for cleaning fabric and the like, which utilizes a nozzle structure comprising an arrangement of one or more jets for co-mixing air and cleaning fluid to cause the cleaning fluid to become reduced to very small particles for effective penetration of the surface material to be cleaned. The patent discloses that an air stream is drawn into the nozzle to engage the leading edge of the stream of cleaning fluid as it moves into engagement the surface to be cleaned. The air stream is indicated to have such force as to cause a deflection of the cleaning fluid stream so as to engage the surface to be cleaned at an angle to be, in effect, swept into and through the material to be cleaned in a continuous moving action, which is stated to leave very little residue of dampness in the cleaned area.
While it would appear that the aforementioned methods and apparatus disclose useful improvements in the art of fabric cleaning, further improvements are desired, particularly in methods and apparatus for simplifying and economically cleaning such surfaces.